diff --git a/src/FitRideFile.cpp b/src/FitRideFile.cpp
index 1f882a512..0926b9c45 100644
--- a/src/FitRideFile.cpp
+++ b/src/FitRideFile.cpp
@@ -640,6 +640,7 @@ struct FitFileReaderState
                         read_unknown( field.size, &count );
                         v = NA_VALUE;
                         unknown_base_type.insert(field.num);
+                        size = field.size;
                 }
                 // Quick fix : we need to support multivalues
                 if (size < field.size)